This invention concerns garden landscaping. More particularly, it concerns support posts for use in the construction of retaining walls and/or fences used in garden landscaping.
Conventional practice in garden landscaping when erecting retaining walls is to construct the retaining wall or walls using bricks, or stones, and mortar. If the retaining wall does more than simply form the edge of a garden bed, it is an inherently expensive structure and takes a considerable time to erect. Consequently, large retaining walls are usually permanent garden structures.
To facilitate the construction of such large retaining walls, special bricks or blocks have been proposed. Recent examples of such bricks or blocks are described in the specification of the U.S. Pat. No. 5,456,555 (angular building blocks); in WIPO Publication No. WO 95/23897 (the specification of International patent application No. PCT/US95/02543-modular wall block system); and in the specification of Australian patent No. 665,923 (interlocking bricks).
Large retaining walls are also constructed using heavy timber. In Australia, treated logs and so-called xe2x80x9crailway sleepersxe2x80x9d have been used in garden landscaping. The specification of Australian patent application No. 27444/92 describes landscaping logs adapted to be combined together and fastened to each other to form a retaining wall structure.
Another type of large retaining wall is constructed using boards, panel members, planks or the like positioned between specially shaped posts. For example, posts having a T cross-section are erected along the required line of the retaining wall with the top arm of the xe2x80x9cTxe2x80x9d aligned with the wall direction and the vertical arm of the xe2x80x9cTxe2x80x9d at a right angle to the wall direction. Planks, panels, and even logs may then be positioned with their ends abutting (or nearly abutting) the inwardly directed arms of the T-section posts to form a wall. Such retaining wall constructions are featured in, for example,
(a) the specification of Australian patent application No. 12612/88 (in which the T-section posts are provided with an elongated base and a vertical plate, to enable earth or other fill to stabilise the frames formed with the T-section posts);
(b) WIPO Publication No. WO 95/13431 (the specification of International patent application No. PCT/AU94/00692, in which the T-section posts are constructed using T-section modular units, with varying lengths of the xe2x80x9cverticalxe2x80x9d arm of the xe2x80x9cTxe2x80x9d, and are restrained by a footing and a xe2x80x9cdeadmanxe2x80x9d anchor arrangement); and
(c) WIPO Publication No. WO 84/04768 (the specification of International patent application No. PCT/US84/00781, in which concrete T-posts are assembled with post-tensioning devices and the stability of the retaining wall is achieved with base members onto which soil or other fill is placed).
A similar retaining wall construction uses posts which include a channel member each side of the post. A number of these posts are erected along the required line of the retaining wall. Panel members, planks or the like, each having a length essentially the same as the distance between adjacent posts of the wall, are then mounted with their ends inside the facing channels of adjacent posts. Suitable bracing or anchoring means are provided, then soil or other fill is placed behind the panels or planks. Examples of such constructions are described in the following documents:
1. The specification of U.S. Pat. No. 5,671,584, to John F Mueller. This specification discloses the use of xe2x80x9cH-beamxe2x80x9d post members, which are post members specially constructed to have a central cavity so that the post members can be placed over respective stakes which have been driven into the ground along the required line of the retaining wall. There is a channel on each side of the xe2x80x9cH-beamxe2x80x9d post. A retaining wall is constructed by sliding the ends of a plank into the facing channels of adjacent xe2x80x9cH-beamxe2x80x9d posts, then repeating this procedure with additional planks. If necessary, anchors connected by cables to holes in the xe2x80x9cH-beamxe2x80x9d posts are used to ensure that the retaining wall remains upright after back-filling.
2. The specification of Australian patent application No. 54785/96, by M. Vincentini and G. Belladonna. This specification discloses a retaining wall constructed by sliding panel members into channelsxe2x80x94groovesxe2x80x94in upright post members formed by folding lengths of sheet metal.
3. WIPO Publication No. WO 99/20846 (the specification of International patent application No. PCT/CA98/00961 by Durisol, Inc.). This document describes the construction of a retaining wall with posts that have channels formed by two flanges connected by a web, which are held in position by anchors that are similar to the anchor of Mueller""s retaining wallxe2x80x94see the aforementioned specification of U.S. Pat. No. 5,671,584.
4. The specification of Australian patent application No. 81448/75, which describes a sea retaining wall formed using panelsxe2x80x94baffle elementsxe2x80x94which are inserted into the channels of a series of I-beams that have been driven into the earth, with a series of xe2x80x9cearth weight anchoring support elementsxe2x80x9d extending rearwardly from the baffle elements.
5. The specification of Australian patent No. 697,901, to Armstrong and McGovern Limited of New Zealand. This specification discloses how sheet metal panels are progressively lowered into the grooves of adjacent piles, to form a retaining wall, as the region in front of the retaining wall is excavated.
6. The specification of U.S. Pat. No. 3,193,255 of H. D. Burdett, which describes a channelled post and plank system, to form a fence.
The first paragraph of the aforementioned specification of Australian patent application No. 81448/75, filed in May 1975, begins:
xe2x80x9cPrior to the present invention, there have existed numerous complicated and impractical sorts of retaining walls from the standpoint of required strength and durability while concurrently being of simple structure . . . that may be mass produced and shipped and assembled on site, with a minimum of experience . . . xe2x80x9d
That statement could well begin the present specification, as a reference to retaining walls used in garden landscaping today.
It is an objective of the present invention to provide a support post for a retaining wall which enables the retaining wall to be constructed more economically, in a significantly shorter time, and with the facility to remove the retaining wall without difficulty or to change the position of the retaining wall should a revised garden landscape be required in the future.
It should be noted that in this specification, including the claims, the terms xe2x80x9cupperxe2x80x9d, xe2x80x9clowerxe2x80x9d, xe2x80x9ctopxe2x80x9d, xe2x80x9cbottomxe2x80x9d, xe2x80x9cverticalxe2x80x9d, and other xe2x80x9cdirectionalxe2x80x9d terms, will be used in the sense that these terms will have when the invention is used in the construction of a retaining wall. In addition, the term xe2x80x9cwall memberxe2x80x9d will mean a generally elongate member, preferably of substantially uniform width, such as a plank or beam (typically, but not necessarily, of wood), having, at least at each end thereof, a flat face, the plane of each flat face being orthogonal to the elongate direction of the member.
The above-mentioned objective is achieved by providing a support post in the form of a plate member which has at least one hole in it through which a bolt, screw or heavy gauge nail can pass to hold a wall member firmly against the plate member. The plate member is pointed at its lower end so that it can be driven into the ground a distance which is sufficient to ensure that the post, when free-standing, will be a rigid and substantially vertical support for the wall member or wall members. The plate member may be formed with at least one stiffening or reinforcing feature, which may be a length of metal rod or angle iron, or may be a fold or ridge, extending the length of the plate member. A spike extending below the point of the plate may be provided, to assist (a) in the penetration of the ground, and (b) in ensuring that the support post is substantially vertical. If such a spike is present, it may be formed integrally with the plate member or it may be bonded to the plate member (for example, by welding).
Thus, according to the present invention, a support post for use in the construction of a retaining wall comprises, in its broadest form, a single rigid, elongate plate member, having a top edge, two side edges and a bottom edge, characterised in that
(a) said bottom edge is pointed;
(b) said plate member has a lower plate portion which, when said support post is in use in the construction of a retaining wall, is inserted into the ground;
(c) said plate member has an upper plate portion, extending from the top of said lower plate portion to said top edge, said upper plate portion, when said support post is in use in the construction of a wall, being positioned adjacent to a wall member of said retaining wall; and
(d) at least one aperture is provided in said upper plate portion, through which a respective securing means (for example, a bolt, screw or the like) may be passed to secure a wall member of said retaining wall to said plate member.
The point (which may be a chisel point) of the bottom edge may be extended downwardly to form a spike.
Normally, the support post will be symmetrical about an imaginary vertical line extending from the centre of the top edge through the point of the bottom edge, and the side edges will be substantially parallel to each other or downwardly slightly divergent or convergent. However, for decorative purposes, the side edges may be non-linear, and may be smoothly shaped so that it is not always possible to observe where the upper edge of the plate member ends and each side edge begins.
When intended for use at a corner of a retaining wall, the plate of the support post may be non-planar. In this configuration, the plate member will normally comprise two substantially identical xe2x80x9chalf-platesxe2x80x9d, each extending from the vertical line of symmetry of the support post. The included angle between the half-plates of the support post need not be a right angle, but should be a right angle when the support post is to be used at a right-angled corner of a retaining wall.
A rod-like extension of the support post above its top edge may be provided. When the support post is symmetrical about a vertical line of symmetry, the rod-like extension will be substantially colinear with the vertical line of symmetry. Such an extension will normally have one or more grooves, or holes, in it, for use in locating a wire, cable or hose that is to be positioned above the retaining wall. Alternatively, the extension may terminate in a threaded boss.
In one embodiment of the support post of the present invention, the plate member is attached to a vertical rod along the vertical line of symmetry. In another realisation of the present invention, two separate xe2x80x9chalf-platesxe2x80x9d are welded to a vertical rod. In these forms of the present invention, the vertical rod will normally extend below the point of the bottom edge of the support post to provide the aforementioned spike, and will be independently pointed at its lowermost end. The rod may also extend upwardly above the top edge of the support post.
If the plate member is roll formed from steel plate, it is preferably formed with a central vertical fold or ridge, to provide extra stiffness to the plate member. A short cylinder may be welded within the ridge or fold, at the top of it to facilitate driving the lower portion of the plate member into the ground. Alternatively, a vertical rod may be positioned (and welded) within the ridge or fold, with an extension below the bottom edge of the plate member, to form a spike.
Several embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings.